BACKGROUND AND OBJECTIVES

Experts hypothesized increased weight gain in children associated with the coronavirus disease 2019 (COVID-19) pandemic. Our objective was to evaluate whether the rate of change of child body mass index (BMI) increased during the COVID-19 pandemic compared with prepandemic years.

METHODS

The study population of 1996 children ages 2 to 19 years with at least 1 BMI measure before and during the COVID-19 pandemic was drawn from 38 pediatric cohorts across the United States participating in the Environmental Influences on Child Health Outcomes-wide cohort study. We modeled change in BMI using linear mixed models, adjusting for age, sex, race, ethnicity, maternal education, income, baseline BMI category, and type of BMI measure. Data collection and analysis were approved by the local institutional review board of each institution or by the central Environmental Influences on Child Health Outcomes institutional review board.

RESULTS

BMI increased during the COVID-19 pandemic compared with previous years (0.24 higher annual gain in BMI during the pandemic compared with previous years, 95% confidence interval 0.02 to 0.45). Children with BMI in the obese range compared with the healthy weight range were at higher risk for excess BMI gain during the pandemic, whereas children in higher-income households were at decreased risk of BMI gain.

CONCLUSIONS

One effect of the COVID-19 pandemic is an increase in annual BMI gain during the COVID-19 pandemic compared with the 3 previous years among children in our national cohort. This increased risk among US children may worsen a critical threat to public health and health equity.

WHAT’S KNOWN ON THIS SUBJECT

The coronavirus disease 2019 pandemic may have increased the risk of excess weight gain for children, potentially because of the closures of schools and recreational facilities with a consequent reduction of physical activity and dietary changes.

WHAT THIS STUDY ADDS

This analysis documents an increase in the rate of body mass index change during the coronavirus disease 2019 pandemic compared with previous years, particularly among children who were obese. Higher household income was protective of pandemic-related body mass index increases.

Childhood obesity is a serious problem with long-term health and quality of life concerns; nearly 1 in 5 US children were categorized as obese in 2018.1  Starting in March 2020, the widespread closure of schools, recreation facilities, and recreational or sports activities because of the coronavirus disease 2019 (COVID-19) pandemic may have resulted in decreased physical activity and altered dietary habits in children, placing them at higher risk for excess weight gain.2,3  Before the COVID-19 pandemic, higher rates of weight gain among school-aged children across the United States were observed during the summer months, when children are out of school, particularly among children who are overweight or obese and among racial and ethnic groups at a higher risk of obesity.48  The Structured Days Hypothesis explains this weight gain as due to changes to or lack of structured opportunities for physical activity through school physical education classes, recess, or recreational sports activities, the loss of regulated meal times and limits on amount and types of food, and more obesogenic screen time and sleep routines9 ; these changes were also present as the pandemic disrupted normal school and childcare routines. Such weight gain is problematic because it is maintained at least through the following school year,5  and, in general, weight gain in childhood is predictive of later risk of being overweight and obese into adulthood,10,11  with later health consequences. In this context, public health and obesity experts have expressed concern that a byproduct of the COVID-19 pandemic-related shutdowns will be excess weight gain among children.1215 

Two recently published US studies have revealed that these concerns are well-founded; using medical records data, Woolford et al in Southern California and Lange et al, using data from children across the United States, showed an accelerated rate of weight gain and increased body mass index (BMI) among children during the pandemic period.16,17  A study of children who had their height and weight measured at school revealed accelerated weight gain during the pandemic year compared with prepandemic years18 ; in particular, accelerated weight gain was demonstrated among children in the healthy BMI category. Similar results have been reported internationally. A retrospective survey of 10 082 adolescents and young adults in China reported increases in BMI during the pandemic.19  In another survey in Turkey, conducted after the start of the COVID-19 pandemic, 42% of parents reported that their child gained weight, compared with 55% reporting no change in weight, within a 3-week lockdown period.20 

There are some limitations to current knowledge regarding excess weight gain in children during the COVID-19 pandemic. First, the US studies were carried out using medical records or in a school setting and had limited information available on child/household socioeconomic status (SES). Given the disproportionate impact of both the obesity epidemic as well as COVID-19 pandemic-related hardships on children from lower socioeconomic status levels, it is important to consider SES in examining changes in BMI.21,22  Second, during the pandemic, many families had limited ability to attend a medical visit. Therefore, studies using solely medical records data may not fully reflect the experiences of the broader US population.

The Environmental Influences on Child Health Outcomes (ECHO)-wide Cohort Study brings together long-standing prospective child cohorts in the United States with the goal of investigating the effects of environmental exposures on child health outcomes.23  Leveraging prospectively collected cohort study data, our objective in this analysis was to evaluate changes in children’s BMI from the prepandemic to the pandemic period. Specifically, we evaluated whether children exhibited accelerated weight gain during the COVID-19 pandemic (March 2020 through May 2021), when many schools were closed and recreational activities curtailed, compared with the prepandemic years (October 2017 through February 2020).

The study population was drawn from the ECHO-wide Cohort Study, a consortium of 69 pediatric cohort studies across the United States.23,24  A central and cohort-specific institutional review board monitored human subject activities at each cohort site and the centralized ECHO Data Analysis Center. All participants provided informed consent.

Children’s weight and height were obtained by each cohort from measurements taken at the cohort study visit, medical record abstraction, or self- or parent-reported measurements. Height and weight were used to calculate BMI (BMI; kg/m2) and percentiles.25,26  We use BMI as the outcome because it is considered most appropriate for the comparison of BMI changes across time.2729  Centers for Disease Control and Prevention cutoffs were used to determine implausible measures, which were excluded from analysis.25  BMI category was defined according to Centers for Disease Control and Prevention guidelines for defining childhood weight status based on BMI percentiles for age and sex: underweight (<5%), healthy weight (5–<85%), overweight (85–<95%), and obese (≥95%).30 

For this analysis, the COVID-19 “pandemic period” was defined as the 15-month period from March 1, 2020, to May 31, 2021, during which the COVID-19 pandemic caused many disruptions to daily routines. The baseline, or “prepandemic period” was between October 1, 2017 and February 29, 2020. A total of 1996 children from 38 cohorts, representing 53 recruitment sites across the United States, who contributed at least 1 BMI in both the prepandemic and the pandemic study periods, comprised the primary analytic sample (Fig 1).

FIGURE 1

Map of participating enrollment sites.

FIGURE 1

Map of participating enrollment sites.

Close modal

Child date of birth was collected at participant registration and age at assessment was recorded continuously in years. Categorical variables included child sex at birth (male, female), the highest level of maternal education attained (less than high school, high school or GED equivalent, or at least some college or more), annual household income (<$30 000, $30 000–$49 999, $50 000–$74 999, ≥$75 000), and child race and ethnicity (reported by the parent or child as non-Hispanic White, non-Hispanic Black, non-Hispanic other race, Hispanic), which we consider a proxy for exposure to structural racism that shapes a range of resources such as housing, education, and employment.31  All sociodemographic variables were collected via self-report or medical record abstraction. A binary pandemic period indicator was introduced to reflect whether a BMI measure was taken during the pandemic period (March 2020 through May 2021) or the prepandemic period (October 2017 through February 2020).

We tabulated participant characteristics in the primary analytic sample for the baseline prepandemic period. For continuous variables (child age, BMI, change in BMI), means and standard deviations were calculated. The number of participants and percentages were reported for categorical variables (sex, race and ethnicity, maternal education level, household income level, type of BMI measure, and BMI category).

To examine trends in BMI before and during the pandemic, we employed linear mixed effects models to compare the annual change in BMI between the prepandemic period and the pandemic period. All models included calendar year, child age, child sex, child race and ethnicity, maternal education, type of measurement (study measure, medical record, or self/parent report), baseline BMI category, household income level, and an indicator for pre- or postpandemic time period, with a random intercept for each child participant and for the cohort. Missing data on income, race, and maternal education were imputed by using the Multivariate Imputation by Chained Imputation (MICE) package in R, with all other variables from the analytic models included as predictors. Results were pooled after 10 iterations.32  Our key parameter of interest was an interaction term between the pandemic year indicator and calendar year, which represents the change in slope (rate of BMI change) between the COVID and pre-COVID time periods. To evaluate whether the rate of BMI change during the pandemic differed by key subgroups (race, ethnicity, baseline BMI category, and household income), we employed interaction terms between the pandemic year indicator, calendar year, and the subgroup of interest.

All analyses were completed in R version 4.1.0 (May 18, 2021). Mixed effects models were fit using the Fitting Linear Mixed-Effects Models (lme4) package.33 

Sensitivity Analyses

We conducted 3 additional analyses to evaluate the robustness of our main findings to key assumptions. First, because our study inclusion criteria required completing an in-person or virtual cohort study visit during the pandemic period, we explored whether children who returned for a study visit had different sociodemographic attributes than those who were not seen during the COVID-19 pandemic. Second, we repeated our primary models using 2 time periods that were both before the COVID-19 pandemic to evaluate whether the BMI changes we observed were due to the COVID-19 pandemic or instead because of secular trends in BMI change. Last, we conducted our main analysis among children with study-measured anthropometric measures only to determine if changes to BMI ascertainment during the pandemic influenced our results. Additional details and results of these analyses are provided in the Supplemental Information.

Of the 1996 children in the primary analytic sample, the mean baseline (prepandemic) age was 5.9 years (SD: 3.4 years) (Table 1). Half (n = 975) were female, and 53% were non-Hispanic White, 15% non-Hispanic Black, and 16% of Hispanic ethnicity. The majority (85%) of mothers reported some college or a higher level of education, and 49% reported a household income of $75 000 or more. Most children (70%) had a baseline BMI in the healthy weight range.

TABLE 1

Sociodemographic Characteristics of Analytic Samplea in the Pre-COVID-19 Pandemic Period

Characteristic
Children 1996 
Child age in 2018, mean ± SD 5.9 ± 3.4 
Sex at birth, female, n (%) 975 (49) 
Race and ethnicity, n (%)  
 Missing 8 (0.4) 
 Non-Hispanic White 1067 (53) 
 Non-Hispanic Black 299 (15) 
 Non-Hispanic other 294 (15) 
 Hispanic, all races 328 (16) 
Maternal education, n (%)  
 Missing 42 (2) 
 Less than high school 70 (4) 
 High school degree, GED or equivalent 178 (9) 
 Some college and aboveb 1706 (85) 
Income, n (%)  
 Missing 294 (15) 
 <$30 000 248 (12) 
 $30 000–$49 999 228 (11) 
 $50 000–$74 999 255 (13) 
 ≥$75 000 971 (49) 
BMI category, n (%)  
 Underweight, <5th percentile 120 (6) 
 Healthy wt, 5–85th percentile 1400 (70) 
 Overweight, 85–95th percentile 244 (12) 
 Obese, ≥95th percentile 232 (12) 
BMI, prepandemic, mean ± SD 17.05 ± 3.31 
BMI, during pandemic, mean ± SD 18.30 ± 4.68 
Change in BMI, pre-/during pandemic, mean ± SD 1.14 ± 2.79 
BMI ascertainment method prepandemic, n (%)  
 Self-report 80 (3) 
 Parent-report 113 (4) 
 Medical record 423 (14) 
 Study measure 2431 (80) 
BMI ascertainment method during pandemic, n (%)  
 Self-report 591 (28) 
 Parent-report 433 (20) 
 Medical record 27 (1) 
 Study measure, n (%) 1092 (51) 
Characteristic
Children 1996 
Child age in 2018, mean ± SD 5.9 ± 3.4 
Sex at birth, female, n (%) 975 (49) 
Race and ethnicity, n (%)  
 Missing 8 (0.4) 
 Non-Hispanic White 1067 (53) 
 Non-Hispanic Black 299 (15) 
 Non-Hispanic other 294 (15) 
 Hispanic, all races 328 (16) 
Maternal education, n (%)  
 Missing 42 (2) 
 Less than high school 70 (4) 
 High school degree, GED or equivalent 178 (9) 
 Some college and aboveb 1706 (85) 
Income, n (%)  
 Missing 294 (15) 
 <$30 000 248 (12) 
 $30 000–$49 999 228 (11) 
 $50 000–$74 999 255 (13) 
 ≥$75 000 971 (49) 
BMI category, n (%)  
 Underweight, <5th percentile 120 (6) 
 Healthy wt, 5–85th percentile 1400 (70) 
 Overweight, 85–95th percentile 244 (12) 
 Obese, ≥95th percentile 232 (12) 
BMI, prepandemic, mean ± SD 17.05 ± 3.31 
BMI, during pandemic, mean ± SD 18.30 ± 4.68 
Change in BMI, pre-/during pandemic, mean ± SD 1.14 ± 2.79 
BMI ascertainment method prepandemic, n (%)  
 Self-report 80 (3) 
 Parent-report 113 (4) 
 Medical record 423 (14) 
 Study measure 2431 (80) 
BMI ascertainment method during pandemic, n (%)  
 Self-report 591 (28) 
 Parent-report 433 (20) 
 Medical record 27 (1) 
 Study measure, n (%) 1092 (51) 
a

Children are included in the primary analytic sample if they had at least 1 BMI in both the prepandemic period (October 2017 through February 2020) and the pandemic period (March 2020 through May 2021).

b

Includes some college with no degree, Associate degrees (AA, AS), trade school, or higher levels of education.

Mean BMI in the prepandemic period was 17.05 (SD 3.3), and an average of 2.6 BMI measures per child were reported across the study period. Prepandemic, 80% of BMI measures were ascertained through study measurement compared with 51% of during-pandemic BMI measures. Prepandemic, 7% of BMI measures were parent- or self-reported and 14% were by medical record abstraction, whereas during the pandemic, 48% were by parent- or self-report and 1% were by medical record abstraction.

No annual increase in BMI was observed before the pandemic after adjusting for age, sex, race, ethnicity, maternal education, household income, type of BMI measure, and baseline BMI category (-0.04 change in BMI per year, 95% confidence interval [CI]: -0.15 to 0.07). During the pandemic, the annual change in BMI was 0.24 higher than during the prepandemic period (95% CI 0.02 to 0.45) (Table 2, Model A). Higher rates of BMI increase during the COVID-19 pandemic period were observed among obese, compared with healthy weight, children. The annual change in BMI during the pandemic, compared with prepandemic, among obese children was 1.12 (95% CI 0.47 to 1.77) higher than among healthy weight children (Table 2, Model B). There was no observed increase in the rate of change in BMI during the pandemic for Black Children, Hispanic children, or overweight children (Table 2, Models D and B). Children in households with an income of ≥$75 000 had decreases in the rate of BMI change during the pandemic (-0.83, 95% CI -1.53 to -0.14) (Table 2, Model C).

TABLE 2

Longitudinal Associations with Change in BMI from October 2017 to May 2021 (n = 1996 Children)a

Model AbModel BbModel CbModel Db
Change in BMI     
 Prepandemic change in BMI per year −0.04 (−0.15 to 0.07) −0.01 (−0.13 to 0.12) −0.1 (−0.42 to 0.21) −0.05 (−0.2 to 0.1) 
 Excess change in BMI during pandemic 0.24 (0.02 to 0.45) 0.16 (−0.09 to 0.41) 0.83 (0.2 to 1.45) 0.26 (−0.04 to 0.56) 
 Excess change in BMI during pandemic among overweight children — −0.39 (−1.05 to 0.27) — — 
 Excess change in BMI during pandemic among obese children — 1.12 (0.47 to 1.77) — — 
 Excess change in BMI during pandemic among children in households with income of $30 00–$50 000 — — −0.01 (−0.95 to 0.93) — 
 Excess change in BMI during pandemic among children in households with income of $50 000–$75 000 — — −0.25 (−1.09 to 0.58) — 
 Excess change in BMI during pandemic among children in households with income of $75 000 — — −0.83 (−1.53 to −0.14) — 
 Excess change in BMI during pandemic among Hispanic children — — — 0.09 (−0.5 to 0.69) 
 Excess change in BMI during pandemic among Black children — — — 0.28 (−0.35 to 0.92) 
Baseline characteristics     
Race/ethnicity (REF: non-Hispanic White)     
 Non-Hispanic Black 0.55 (0.23 to 0.88) 0.55 (0.22 to 0.87) 0.54 (0.22 to 0.87) 0.13 (−0.65 to 0.91) 
 Non-Hispanic other race 0.15 (−0.13 to 0.43) 0.15 (−0.13 to 0.43) 0.13 (−0.15 to 0.41) −0.03 (−0.79 to 0.73) 
 Hispanic, all races 0.13 (−0.16 to 0.41) 0.13 (−0.15 to 0.41) 0.12 (−0.17 to 0.4) 0.09 (−0.61 to 0.78) 
Income (REF: <$30 000)     
 $30 000–$50 000 −0.26 (−0.65 to 0.13) −0.25 (−0.64 to 0.13) −0.39 (−1.42 to 0.65) −0.25 (−0.64 to 0.14) 
 $50 000–$75 000 −0.29 (−0.69 to 0.11) −0.28 (−0.67 to 0.11) −0.28 (−1.32 to 0.75) −0.28 (−0.68 to 0.12) 
 ≥$75 000 −0.68 (−1.04 to −0.32) −0.68 (−1.03 to −0.32) −0.21 (−1.08 to 0.66) −0.68 (−1.04 to −0.32) 
BMI category at baseline (REF: healthy weight)     
 Overweight 2.87 (2.59 to 3.16) 2.71 (1.93 to 3.49) 2.88 (2.6 to 3.16) 2.88 (2.59 to 3.16) 
 Obese 6.93 (6.64 to 7.23) 7.19 (6.43 to 7.95) 6.94 (6.65 to 7.24) 6.93 (6.64 to 7.23) 
Intercept 14.13 (13.42 to 14.84) 14.11 (13.39 to 14.83) 13.96 (12.99 to 14.93) 14.27 (13.53 to 15.02) 
Model AbModel BbModel CbModel Db
Change in BMI     
 Prepandemic change in BMI per year −0.04 (−0.15 to 0.07) −0.01 (−0.13 to 0.12) −0.1 (−0.42 to 0.21) −0.05 (−0.2 to 0.1) 
 Excess change in BMI during pandemic 0.24 (0.02 to 0.45) 0.16 (−0.09 to 0.41) 0.83 (0.2 to 1.45) 0.26 (−0.04 to 0.56) 
 Excess change in BMI during pandemic among overweight children — −0.39 (−1.05 to 0.27) — — 
 Excess change in BMI during pandemic among obese children — 1.12 (0.47 to 1.77) — — 
 Excess change in BMI during pandemic among children in households with income of $30 00–$50 000 — — −0.01 (−0.95 to 0.93) — 
 Excess change in BMI during pandemic among children in households with income of $50 000–$75 000 — — −0.25 (−1.09 to 0.58) — 
 Excess change in BMI during pandemic among children in households with income of $75 000 — — −0.83 (−1.53 to −0.14) — 
 Excess change in BMI during pandemic among Hispanic children — — — 0.09 (−0.5 to 0.69) 
 Excess change in BMI during pandemic among Black children — — — 0.28 (−0.35 to 0.92) 
Baseline characteristics     
Race/ethnicity (REF: non-Hispanic White)     
 Non-Hispanic Black 0.55 (0.23 to 0.88) 0.55 (0.22 to 0.87) 0.54 (0.22 to 0.87) 0.13 (−0.65 to 0.91) 
 Non-Hispanic other race 0.15 (−0.13 to 0.43) 0.15 (−0.13 to 0.43) 0.13 (−0.15 to 0.41) −0.03 (−0.79 to 0.73) 
 Hispanic, all races 0.13 (−0.16 to 0.41) 0.13 (−0.15 to 0.41) 0.12 (−0.17 to 0.4) 0.09 (−0.61 to 0.78) 
Income (REF: <$30 000)     
 $30 000–$50 000 −0.26 (−0.65 to 0.13) −0.25 (−0.64 to 0.13) −0.39 (−1.42 to 0.65) −0.25 (−0.64 to 0.14) 
 $50 000–$75 000 −0.29 (−0.69 to 0.11) −0.28 (−0.67 to 0.11) −0.28 (−1.32 to 0.75) −0.28 (−0.68 to 0.12) 
 ≥$75 000 −0.68 (−1.04 to −0.32) −0.68 (−1.03 to −0.32) −0.21 (−1.08 to 0.66) −0.68 (−1.04 to −0.32) 
BMI category at baseline (REF: healthy weight)     
 Overweight 2.87 (2.59 to 3.16) 2.71 (1.93 to 3.49) 2.88 (2.6 to 3.16) 2.88 (2.59 to 3.16) 
 Obese 6.93 (6.64 to 7.23) 7.19 (6.43 to 7.95) 6.94 (6.65 to 7.24) 6.93 (6.64 to 7.23) 
Intercept 14.13 (13.42 to 14.84) 14.11 (13.39 to 14.83) 13.96 (12.99 to 14.93) 14.27 (13.53 to 15.02) 

REF, reference group; —, coefficient not estimated in this model.

a

Children are included in the primary analytic sample if they had at least 1 BMI in both the prepandemic period (October 2017 through February 2020) and the pandemic period (March 2020 through May 2021).

b

In addition to the factors shown above, all models adjusted for age, sex, maternal education (less than high school, high school or GED equivalent, or at least some college or more), type of BMI measure (self-report, parent-report, medical record, or study measure), and an indicator for pre- or during COVID pandemic period. Models B through D also include group-specific estimates of the prepandemic change in BMI.

Completing a cohort study visit during the COVID-19 pandemic (whether in-person or by teleconference/telephone) was a burden that we hypothesized would be met by a population that would be sociodemographically different from the overall group of cohort enrollees. To test this hypothesis, we compared our primary analytic sample to the larger group of children enrolled in ECHO who had study visits during our prepandemic period but not during the COVID-19 pandemic period (Supplemental Table 3). Our primary sample differed from our comparison sample in several important respects. The comparison sample had a higher proportion of Hispanic children (21% compared with 16% in the primary analytic sample) and a lower proportion of non-Hispanic White children (49% compared with 53%). The comparison sample had lower maternal education (81% with some college or more) and lower annual household income (38% with ≥$75 000).

In our second sensitivity analysis to determine if there were temporal trends in BMI change before the COVID-19 pandemic that may explain our main results, we observed no increase in BMI during the first half of the prepandemic period and no statistically significant difference in slope in the final year of the prepandemic period (Supplemental Table 4). In other words, the COVID-19 pandemic period appears to have a unique effect on trends in BMI among our study sample.

In our third sensitivity analysis, in the subsample of 1052 children who had study-measured height and weight before and after the COVID-19 pandemic, similar results are observed as in our primary analytic sample (Supplemental Table 4); there was a statistically significant increase in the change in BMI in the COVID-19 pandemic period as compared with previous years after restricting to children with a study measured height and weight only (Supplemental Table 4; 0.42, 95% CI 0.1 to 0.74).

Our study reveals that one important effect of the COVID-19 pandemic is an increase in annual BMI change during the COVID-19 pandemic period compared with the three previous years among children in our national cohort. Using a population combined from multiple prospective cohort studies, our findings underscore what other studies have revealed both within1618,34,35  and outside of the United States.13,3638  We find that the COVID-19 pandemic period was associated with an excess increase in BMI of 0.24 kg/m2 per year more than in the previous prepandemic period, even when controlling for socioeconomic status, race and ethnicity, baseline BMI category, and type of BMI ascertainment. Our findings validate the predictions of many scholars that weight would increase among children because of the cumulative effects of anticipated decreases in physical activity and increases in sedentary behavior, screen time, and high-calorie diets among children during the pandemic.12  Importantly, our study is the first to reveal this excess weight gain while controlling for individual SES, an important known predictor of obesity among children.

Alongside the COVID-19 pandemic, our data also highlight known risks of higher BMI among children reporting Black race and lower annual household income. Racial, ethnic, and socioeconomic disparities in obesity prevalence in the United States have been well-documented, resulting in a disproportionate burden of physical and mental health consequences of obesity among vulnerable children and adults, reflecting exposure to structural racism and other social and economic determinants of health.39  The COVID-19 pandemic has also disproportionately affected these same higher-risk groups in terms of both mortality and morbidity from COVID-19 infections in their families and communities.40  Our study did not find widening disparities in BMI increase during the pandemic among Black or Hispanic children. It is important to note that these groups only comprised 15% and 16% of our sample size, respectively, so we may have been underpowered to detect differences among these subgroups. We encourage ongoing investigation of potential disparities among racial and ethnic minority children due to the pandemic. We observed increasing disparities due to socioeconomic position. Children living in households in the highest income category experienced decreases in BMI during this time, perhaps reflecting greater access to green space, nutritious foods, and other material conditions conducive to healthy growth. It will be important to collect more data on BMI change in children, specifically among vulnerable subpopulations as the pandemic continues to alter children’s lives, and use these data to inform evidence-based interventions to reduce rather than augment health inequities.

The observed excess increase in BMI among children in our study during the COVID-19 pandemic will lead to a greater propensity for children to transition from a healthy BMI to one that is overweight/obese, which will only exacerbate the epidemic of obesity that is already a major public health concern across the United States. Children who are overweight or obese are known to be at increased risk for poor physical and mental health outcomes.41,42  Once weight is gained it is difficult to lose; thus, much effort has been focused on primary prevention methods for avoiding excess weight gain and obesity during childhood.43  Our study revealed a more pronounced BMI increase during the COVID-19 pandemic among children categorized as obese in the baseline prepandemic period, putting this subgroup at additional increased risk for adverse health outcomes.

We do note that our primary analytic sample is composed of fewer children from higher-risk subgroups than our larger body of children enrolled in ECHO and, therefore, likely also when compared with the general US population. This is not surprising because the children in the primary analytic sample are those that were able to fulfill a cohort study visit during a global pandemic. We suspect that if we had BMI data during the COVID-19 year for our broader ECHO community, we would have witnessed an even greater increase in BMI during the widespread closures associated with the COVID-19 pandemic, as was observed in a recent publication of children living in the United States.16  We call for further research to quantify fully the impact of the pandemic on childhood obesity in the United States.

Our analysis has several limitations. First, we brought together pediatric cohorts with different visit structures; therefore, the timing of measurements of child height and weight was not uniform. Second, the height and weight measurements were assessed differently through either self-report, medical record extraction, or direct measurement by trained study personnel, with and without repeated measurements per visit and/or adherence to ECHO measurement protocols. The method of ascertainment also differed prepandemic and during the pandemic. However, a sensitivity analysis of children with only study-measured height and weight mirrored our main findings. Of note, parent or self-reported weight often underestimates true weight,44,45  and therefore, findings of weight gain in this study that are partially informed by self-reported weight are likely an underestimation of the true weight gain, because a higher proportion of measures were self-report in the pandemic period.

This analysis documents an increase in rate of BMI change during the COVID-19 pandemic in our national cohort of children. We highlight the need for targeted interventions to combat the physical and mental health consequences of the COVID-19 pandemic, particularly among higher-risk communities. Without more vigorous intervention, we can anticipate an exacerbation of the obesity epidemic among US children.

The authors wish to thank our ECHO colleagues, the medical, nursing, and program staff, as well as the children and families participating in the ECHO cohorts. We also acknowledge the contribution of the following ECHO program collaborators:

Coordinating Center: Duke Clinical Research Institute, Durham, North Carolina: PB Smith, KL Newby, DK Benjamin; Data Analysis Center: Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland: LP Jacobson; Research Triangle Institute, Durham, North Carolina: CB Parker; Northeastern University, Boston, Massachusetts: AN Alshawabkeh; Albert Einstein College of Medicine, Bronx, New York: JL Aschner; Massachusetts General Hospital, Boston: CA Camargo; University of Colorado Anschutz Medical Campus, Aurora, Colorado: D Dabelea; Memorial Hospital of Rhode Island, Pawtucket: S Deoni, VA D’Sa; Emory University, Atlanta, Georgia: AL Dunlop, PA Brennan, EJ Corwin; Avera McKennan Hospital and University Health Center, Sioux Falls, South Dakota: AJ Elliott; Kaiser Permanente, Oakland, California: A Ferrara, LA Croen; Vanderbilt University Medical Center, Nashville, Tennessee: T Hartert; Dartmouth College, Hanover, New Hampshire: MR Karagas; University of Washington, Seattle: C Karr, S Sathyanarayana; University of California, San Francisco: KZ Lewinn; NR Bush; University of Tennessee Health Sciences Center: A Mason; Women & Infants Hospital of Rhode Island, Providence: B Lester; University of Oregon, Eugene: LD Leve; Brigham & Women's Hospital, Boston, Massachusetts: AA Litonjua, ST Weiss; Oregon Health & Science University, Portland, Oregon: CT McEvoy, ER Spindel; University of Rochester, New York: TG O’Connor, C Buss, RK Miller, PD Wadhwa; University of North Carolina, Chapel Hill: M O’Shea, R Fry; Columbia University, New York, New York: FP Perera, JB Herbstman; University of Illinois, Urbana: SL Schantz; University of Utah, Salt Lake City: JB Stanford, EB Clark, C Porucznik; Icahn School of Medicine at Mount Sinai, Boston, Massachusetts: RJ Wright, RO Wright.

See acknowledgments for full listing of collaborators.

Drs Knapp and Chandran conceptualized and designed the study, interpreted the data, drafted the initial manuscript, and reviewed and revised the manuscript; Ms Dong conducted the data analysis, created tables and figures, and drafted the initial manuscript; Ms Hodges conducted additional analyses and critically reviewed and revised the manuscript; Drs Ganiban, Gilbert-Diamond, Chen, Alshawabkeh, Teitelbaum, Hartert, Karagas, Gilliland, O’Connor, and Jacobson provided input on the design and implementation of the analysis, interpreted the data, and critically reviewed and revised the manuscript for important intellectual content; Drs Dunlop, Aschner, Stanford, Hudak, Carroll, McEvoy, O’Shea, Carnell, Herbstman, Dabalea, Ferrara, Hedderson, Bekelman, Rundle, Fry, Wright, Camargo, Lester, and Hockett critically reviewed and revised the manuscript for important intellectual content; and all authors approved the final manuscript as submitted and agree to be accountable for all aspects of the work.

FUNDING: Research reported in this publication was supported by the Environmental Influences on Child Health Outcomes (ECHO) program, Office of The Director, NIH, under Award Numbers U2COD023375 (Coordinating Center), U24OD023382 (Data Analysis Center), U24OD023319 (PRO Core), UH3 OD023318 (Dunlop), UH3 OD023320 (Aschner), UH3 OD023249 (Stanford), UH3 OD023282 (Gern), UH3 OD023337 (Wright), UH3 OD023349 (O’Connor), UH3 OD023288 (McEvoy), UH3 OD023348 (O’Shea), UH3 OD023313 (Deoni), UH3 OD023275 (Karagas), UH3 OD023290 (Herbstman), UH3 OD023248 (Dabelea), UH3 OD023389 (Leve), UH3 OD023289 (Ferrara), UH3 OD023251 (Alshawabkeh), UH3 OD023287 (Breton), UH3 OD023279 (Elliott), and UH3 OD023253 (Camargo). The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH. Funded by the National Institutes of Health (NIH).

CONFLICT OF INTEREST DISCLOSURES: The authors have indicated they have no conflicts of interest relevant to this article to disclose.

     
  • BMI

    body mass index

  •  
  • COVID-19

    coronavirus disease 2019

  •  
  • CI

    confidence interval

  •  
  • ECHO

    Environmental Influences on Child Health Outcomes

  •  
  • SES

    socioeconomic status

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Supplementary data